This investigation is concerned with development of techniques for effecting immunoprophylaxis and immunotherapy in syngeneic tumor-host systems, particularly mouse lymphomas. Emphasis will be placed on development of vaccines by modification of cells from the tumor to be treated. Reagents employed for modification reactions will be selected to react with different functional groups (and consequently at different sites on the cell), to introduce strong or weak antigenic determinants, and to alter electrical charge. These preparations will first be used prophylactically to protect mice against challenge with the tumor from which the cells were derived. Those that are protective will then be applied therapeutically to tumor-bearing mice. Therapeutic trials will concentrate on developing a model utilizing chemotherapy and immunotherapy together. Evaluation of the immune response to the vaccines will be undertaken employing tests for humoral and cellular response. Correlations will be sought between results of such testing and ability of host mice to reject a given tumor cell challenge. The immunologic relationship existing between tumor and host will also be examined with a view toward guiding selection of the type of modification reaction and vaccination regimen that may be most beneficial in a given system. Studies with tumor-specific antibodies will be performed to determine their protective capacity and their influence on macromolecule synthesis in the tumor cells. Correlations between these activities will be sought. The therapeutic value of anti-cancer drugs complexed to tumor-specific antibodies will also be investigated.